What is the primary difference between a change in quantity demanded and a change in demand?

• A. Both changes are caused by a change in price.
• B. A change in demand is caused by a change in price, while a change in quantity demanded is caused by other factors.
• C. Both changes are caused by factors other than price.
• D. A change in quantity demanded is caused by a change in price, while a change in demand is caused by other factors.

Answer: (D)